Collector ring



Patented Dec. 18, 1928.

-" UNITEDSTATES PATENT OFFICE.

DAVID J. CONANT, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

COLLECTOR RING.

My invention relates to current-collecting devices and it has particular relation to composite slip rings.

The object of my invention is to make a slip ring having an active surface material of known uniformity, requiring fewer machine operations and consisting of cheaper material than slip rings heretofore known in the art.

Cast brass or bronze slip rings usually contain air holes or sand inclusions which, if present on the finished surfaces, render the rings unsuitable.

Cast-copper slip rings have been utilized but they cannot be utilized alone because the copper stretches in use, probably due to repeated beatings and contractions, so that, eventually, they become loosened from the supporting cylinder on which they are mounted.

It has been customary, in the past, to provide cast-copper slip rings of U or T-shape in cross section, having a steel ring shrunk upon thebase member of the copper ring for the purpose of holding it in clamped engagement against the supporting cylinder and positively preventing the loosening thereof, as set forth in the patent to Siegfried & Jungk, No. 1,281,862, granted October 15, 1918, and assigned to Westing house Electric & Manufacturing Company.

Rolled sheet copper, on the other hand, is a homogeneous material, a good conductor and eminently suited for collector rings except for its property of continually stretch.- ing, as pointed out in the patent to Mills No. 1,393,564, granted October 11, 1921, and assigned to Westinghouse Electric & Manufacturing Company. It has heretofore been impossible, however, to utilize sheet copper for collector rings because of the difiicultics encountered in securing it in place so that it will not work loose in operation.

According to my invention, I utilize a steel inner ring, with sheet copper rolled, spun or pressed over it. My invention is illustrated in the accompanying drawing, wherein Figure 1 is a longitudinal sectional view of a current-collecting device of my invention,

Fig. 2 is an end elevation of the-same in position on the motor shaft, and

Fi s. 3 and 4 are sectional views illustrating t e process of manufacture.

Application filed March 31, 1927. Serial No. 179,762.

As shown in the drawing, my invention comprises a cylindrical member 2 carried by a shaft 3, and one or more slip rings 4 tightsheet 8 of a good conductor, such as copper,

wrapped around said inner ring, as by means of rolling, spinning or pressing operations, whereby a portion 9 of the copper sheet extends inside of the iron ring 7, between the iron ring and the supporting cylindrical member 2 on which the slip ring is mounted. Itwill be further observed that another portion 10 of the copper sheet extends outside of the iron ring, and provides an ideal current-collecting surface for the device.

A convenient method of making the slip ring just described is to place acopper blank 8 between the steel ring 7 and a die 11 having an annular groove 12, as shown in Fig. 3. Suflicient pressure is then applied, through a plate 13, to force the steel ring 7 into the groove 12 of the die, and also to upset the outer portion 10 of the copper ring to a greater thickness than the original blank 8* or the inner portion 9. The copper is thus practically extruded into the die. A thickened surface portion 10 is preferred, in order that a larger quantity of active wearing material may be provided, and also to provide for the trimming of the slip-ring surface. As the slip rings 4 are all made from a die of uniform size, the bores of the finished rings do not require turning before assembly on the supporting cylinder 2.

I claim as my invention:

1. A collector ring for electrical apparatus comprising a steel ring and a continuous sheet of copper bent thereover and extending adjacent to both the inner and outer surfaces of said ring.

2. A current-collecting device comprising a shaft, acylindrical member carried thereby and a slip ring tightly embracing said cylindrical member, said slip ring comprising an inner ring of a material of relatively poor conductivity but capable of retaining its tight fit on said cylindrical member for an indefinitely long period of time and a ing both the inner and outer illl'filren of solid ring. 10 4. An extruded copper v'li rin lizi'ving an embedded iron core.

In testimony whei'eof, I have liervu'tto s libscribed my name this fill: day ol 1927.

llLlil' DAVID J. CONANT. 

